Composition of matter



memes Aug. 13, 1935 2,011,369 COMPOSITION or MATTER Philip M. McKenna,

land County,

Unity Township, Westmore- Pa., assignor to Vanadium-Alloys SteelCompany, Latrobe, Pa., a corporation of Pennsylvania 5 Claims.

The purpose of this invention isto produce "a'ehard metal compositionpossessing desirable qualities of hardness,

for metal cutting tools, particularly steel-cutting tools and tools forcutting other ferrous alloys at high speeds on machines such as ilathes,shapers, milling machines, and hole-drilling and finishing machines;also for wire drawing dies, metal formingdies, guides for spinningthread and twine,

and guideswhich are subjected to wear as "in automatic grindingmachines, wear resisting bearings and pivots in such machines as theAtwood machine, electric meters, clocks, weighing scales and forservices resisting pressure, heat abrasion or chemical destruction, orcombination of any or all of these.

The essential elements of my composition are tantalum carbide andmalleable, ductile tungsten metal, which latter I produce and maintainby a novel process hereinafter disclosed, from a molten tungsten allo'y.

This enables me to produce a mechanically strong composition of tantalumcarbide and tungsten using more than 71% tantalum carbide and less than29% tungsten, possessing greater strength than a composition formed bythe usual process of producing a conglomerate welded mass of tantalumcarbide and tungsten as disclosed in United States Patent No. 1,848,899,granted March 8, 1932.

In the art of producing malleable tungsten it is known that alloying thetungsten with nickel makes makes the tungsten malleable as disclosed inUnited States Patent No. l,l10,303.to Hans Kreusler.

strength and inertness to chemical and physical destructive forceswhich' adapt it to a number of useful purposes, such as about The moltentungsten-nickel alloys are described in the International CriticalTables, Vol. II, page 438, by a diagram showing uniform solutions ofWit; and various eutectics. Referring to this diagram it is seen thatwhile an alloy of 55% tungsten and nickel has a melting point as low as1460" C., that on increasing the tungsten content the melting pointmounts rapidly to temperatures above the disintegration point of cruelble refractories which could be used to melt the binary alloy.Therefore, I found it impracticable to produce ductile tungsten alloysmuch above 55% tungsten by melting.

The improvement in strength of my hard com- I position, when thisductile form of tungsten is used, is marked and as low as 5% of tungstenin this form is sufflcient to produce a tool stron enough to serve as alathe tool for cutting steel, while on the other hand if the tungstenwere added as grains of tungsten metal powder as reduced by hydrogenequalpercentages would not suflice to form an equally durable tool withtantalum carbide.

Heretofore hard compositions of approximately TaC, 10% Ni and 10% W havebeen manufactured by adding grains of tungsten metal powder to thecomposition in the ball mill. In these cases the amount of tungstenwhich can be added is restricted to an amount which can be absorbed bythe amount of nickel used, at the temperature at which the compositionis heated. At about 1400 C., the usual temperature, this is an equalweight of tungsten to the nickel and the temperatures cannot bematerially increased to dissolve a greater proportion of tungstenwithout vaporization of the nickel, especially as the heating is usuallycarried out in a vacuum furnace.

Attempts to add more tungsten as metal powder grains results in adecrease in transverse break strength of the composition due to the factthat the tungsten grains as such weaken the composition, unless thetungsten is in malleable form, as obtains when the tungsten is firstdissolved and then precipitated and filtered out of the nickel by theprocess I hereinafter disclose.

If a greater quantity of tungsten than say 1 0% is put into thecomposition with enough nickel to absorb it, the quantity of nickelnecessary being likewise increased, the efiect of this surplus nickel isto soften the hard compositon to a point where it is not valuable forsteel cutting.

I have found it desirable and necessary to produce the powder oftantalum carbide and metal from which I make the hard composition (bysubsequent heating and pressing) by abrasion of the metal under anon-oxidizing fluid. These conditions I obtain byfirst melting tungstenwith nickel, producing ingots 55% tungsten and 45% nickel. This meltingcan be done conveniently in silica sand crucibles in a high frequencyinduction furnace such as is used for melting nickel, the temperaturerequired being 1460 C.

I melt the nickel first, and then add pure tungsten powder,tie-oxidizing the heat with a little ferro-silicon before pouring. Theseingots may then be cut up into /2" cubes with a thin abrasive wheel.These slugs are then used as grinding balls in a ball mill, in which'thetantalum carbide is ground in a non-oxidizing liquid such as benzene, ormethylene dichloride, the freshly abraded surfaces of the metalparticlesbeing pre- 5 tungsten to 200 grams of tantalum carbide, as anexample. I have found that more than 11% of nickel in the hardcomposition softens it too much, and that 2% to 8% .is more satisfactoryfor a hard composition to resist abrasive cutting. At the same time itis desirable to put in more than 12% tungsten to get the combination ofstrength and hardness desired. The problem then is presented, how togeta higher ratio of tungsten to nickel in the final composition than isobtainable in the nickel-tungsten slugs which must be melted. v

This I have solved by the discovery that by adding manganese to thepowder containing the abraded 55% tungsten 45% nickel alloy and thetantalum carbide, the nickel may be liquidated out in greater partleaving the tungsten concentrated and entrained in the compositon in ahighly desirable malleable form.

The manganese acts by alloying with the nickel, forming a very fluidliquid containing a high percentage of nickel, while the tungsten, orhigh percentage tungsten-alloy, is precipitated out of solution andfiltered out in the finely divided tantalum carbide, throughwhich thefluid nickel manganese alloy passes and is removed from the composition.

I add an amount of manganese from one-tenth to six-tenths of the nickelwhich I wish to remove. For example, I add 5% manganese to a mixcontaining say 13% Ni.

Thus I obtain malleable tungsten in my composition with a higher ratioof tungsten to nickel than can be obtained by adding tungsten powder andnickel to the tantalum carbide.

For example-I ground 150 grains of tantalum carbide, 6.23% carbon, withalloy slugs containing.55% tungsten, 45% nickel, with 7 grams ofmanganese metal, for two and a half days; the powder then containing13%.; per cent nickel and 16.5% tungsten. On heating 100 grams of thispowder, moist with benzene, in a 131 5" square hole in a graphite mold,fitted with a graphite plunger, above the liquefaction temperature ofthe manganese nickel alloy which is about 1300 C. and pressing with 2000lbs. pressure, a hard metal composition analyzing nickel 6.05%, tungsten15.94%, manganese .72%, balance 77.21%

tantalum carbide was formed. The liquid alloy' which was pressed outcontained 69.84% nickel.

This latter alloy was strongly magnetic, unlike the original 55%tungsten, 45% nickel alloy which is unma'gnetic. The pressed out alloycontained 7.72% manganese besides 11.83% tantalum and 10.94% tungsten. I

The hard composition, produced after this treatment resulting in theremoval of part of the nickel, had a Rockwell hardness of 86 A. Thetransverse break strength of this metal was high; a piece 1%" thick x5%" wide supported apart and pressed in the center with a Brinell ballwas unbroken with 3600 kg. load.

Another piece-was formed by heating the same powder to a highertemperature, by several hundred degrees; this produced a piece of myhard composition analyzing nickel .47%, tungsten 23.43% of Rockwellhardness 88 A.

These pieces were tested as lathe tools cutting steel of 302 Brinellhardness at speeds of above 300 feet per minute, on a lathe, the bits ofmetal being brazed to steel shanks for the purpose. They cut for 20minutes without appreciable wear.

For some purposes it will be seen that the harder composition from whichmore nickel has been liquidated is desirable, although to get ductiletungsten it is necessary to leave more than one thirtieth as much nickelas tungsten in the composition, and the durability as a tool is improvedby having less than two-f fths as much nickel as tungsten.

A very important advantage of my improved hard composition of tantalumcarbide, tungsten metal and nickel is that the relative proportions oftungsten and nickel are such that the nickel is absorbed in the tungstenand thus the coefllclent of expansion of the tungsten-nickel is broughtto substantially the same as that of the tantalum carbide and there isthereforeno danger of crack ing during the alternate heating and coolingol.

the material while it is being used for instance as a tool tip incutting steel. If the nickel were not absorbed by the tungsten were notpresent in suflicient amount relative to the nickel to be able to absorbthe nickel, the higher coeflicient of thermal expansion of the nickel,which is approximately two and one-half times that of the tantalumcarbide, would cause such cracking as. the result of thermal expansion.Such required proportions of tungsten and nickel are from one-thirtiethto two-fifths as much nickel as tungsten.

The presence of a small percentage of manganese in the final compositionis beneficial from the standpoint of mechanical strength.

The alloy produced by the liquidation namely, about 70% nickel, 8%manganese, 11% tungsten and 11% tantalum'is in itself a tough alloy,which is particularly adapted to forming a union between the particlesof tantalum carbide and-tungsten, when it is not entirely pressed out.

-I laim- 7 a 1. "A hard unmelted composition of matter for steel-cuttingtodl'sj-dies and the like, wherein the particles are welded together,comprising 71% to 92% of tantalum carbide, 28 0 to 6% 0f tungsten andone-thirtieth to two-fifths as much nickel as tungsten and fromone-fourth to onetwentieth as much manganese as nickel.

2. A hard composition of matter for .steelcutting tools, dies and thelike, comprising about 77% tungsten, about 6% tenths of one per cent ofmanganese. 3. A hard unmelted composition of matter for steel-cuttingtools, dies and the like, wherein the particles are welded together,consisting substantially of tantalum carbide, tungsten metal, nickel andmanganese, the tungsten comprising from 28% to 61% of the mass byweight, the nickel being present in amount of from one-thirtieth totwo-fifths of the tungsten by weight and from one-fourth toone-twentieth as much manganese as nickel by weight.

4. A hard composition of matter for steel cutting tools, dies and thelike, wherein the particles are in welded relation, comprising by weightfrom 71% to 92% of tantalum carbide, from 28% to 6% of tungsten, fromone-thirtieth to two-fifths as much nickel as tungsten, and manganese inappreciable but minor quantities 5. A hard composition of matter forsteelcutting tools, dies and the like, comprising by weight about 77% ofparticles of tantalum carbide, about 16% of tungsten, about 6% of nickeland manganese in an appreciable but minor quantity.

PHILIP M. McKENNA.

and if the tungsten of particles of tantalum carbide, about 16% nickeland about eight- I

